Affinity Determination

The determination of aptamer-target binding characteristics is an important tool in the aptamer discovery process. Affinity determination with Bio-Layer Interferometry (BLI) can be used to select aptamer candidates for specific downstream applications, identify matched aptamer pairs, and optimize buffer formulations. BLI is routinely used for characterization of aptamer candidates and identification of complementary aptamers at Base Pair. Affinity testing is available as part of an aptamer discovery project OR as a stand-alone service. Whether you have discovered aptamers with Base Pair, in your own laboratory, or with another research team, we can assist you with affinity determination.

About Bio-Layer Interferometry (BLI)

Bio-Layer Interferometry (BLI) is an optical technique that measures changes in reflected light caused by binding at the sensor tip. White light is emitted from the sensor. It is reflected back from the sensor tip and a reference layer to a detector. A shift in the interference pattern indicates a change in thickness of the outer layer at the tip. This change is reported as a change in wavelength over time. Only analyte binding to or dissociating from the surface will cause a shift in the interference pattern. The schematic below shows changes in reflected light upon binding of aptamer and target.

Advantages of BLI

Works well in complex buffers and sample matrices

Calculates association rate, dissociation rate, and concentration

Can be used to identify complementary aptamers (aptamer pairs) or aptamers complementary to existing antibodies

BLI Testing at Base Pair

Depending upon the number of aptamers and buffers to be tested, BLI affinity determination is typically completed within one to two weeks of receipt of labeled aptamer candidates and target. Buffers can be shipped to Base Pair or formulation(s) can be provided. Biotin-labeled or amine-labeled aptamers can be tested using standard chip formats, but testing of amine-labeled aptamers is recommended for maximum sensitivity. Custom testing formats are also available. An association constant, dissociation constant, and affinity constant (KD) are reported for each aptamer in each buffer tested.